UXvi7Np0

1import sun.misc.BASE64Decoder;
2import sun.misc.BASE64Encoder;
3
4import javax.crypto.Cipher;
5import javax.crypto.NoSuchPaddingException;
6import javax.crypto.spec.IvParameterSpec;
7import javax.crypto.spec.SecretKeySpec;
8import java.math.BigInteger;
9import java.security.InvalidAlgorithmParameterException;
10import java.security.InvalidKeyException;
11import java.security.MessageDigest;
12import java.security.NoSuchAlgorithmException;
13
14public class Main {
15    private static String md5(final String input) throws NoSuchAlgorithmException {
16        final MessageDigest md = MessageDigest.getInstance("MD5");
17        final byte[] messageDigest = md.digest(input.getBytes());
18        final BigInteger number = new BigInteger(1, messageDigest);
19        return String.format("%032x", number);
20    }
21
22    private Cipher initCipher(final int mode, final String initialVectorString, final String secretKey)
23            throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException {
24        final SecretKeySpec skeySpec = new SecretKeySpec(md5(secretKey).getBytes(), "AES");
25        final IvParameterSpec initialVector = new IvParameterSpec(initialVectorString.getBytes());
26        final Cipher cipher = Cipher.getInstance("AES/CFB8/NoPadding");
27        cipher.init(mode, skeySpec, initialVector);
28        return cipher;
29    }
30
31    public String encrypt(final String dataToEncrypt, final String initialVector, final String secretKey) {
32        String encryptedData = null;
33        try {
34            // Initialize the cipher
35            final Cipher cipher = initCipher(Cipher.ENCRYPT_MODE, initialVector, secretKey);
36            // Encrypt the data
37            final byte[] encryptedByteArray = cipher.doFinal(dataToEncrypt.getBytes());
38            // Encode using Base64
39            encryptedData = (new BASE64Encoder()).encode(encryptedByteArray);
40        } catch (Exception e) {
41            System.err.println("Problem encrypting the data");
42            e.printStackTrace();
43        }
44        return encryptedData;
45    }
46
47    public String decrypt(final String encryptedData, final String initialVector, final String secretKey) {
48        String decryptedData = null;
49        try {
50            // Initialize the cipher
51            final Cipher cipher = initCipher(Cipher.DECRYPT_MODE, initialVector, secretKey);
52            // Decode using Base64
53            final byte[] encryptedByteArray = (new BASE64Decoder()).decodeBuffer(encryptedData);
54            // Decrypt the data
55            final byte[] decryptedByteArray = cipher.doFinal(encryptedByteArray);
56            decryptedData = new String(decryptedByteArray, "UTF8");
57        } catch (Exception e) {
58            System.err.println("Problem decrypting the data");
59            e.printStackTrace();
60        }
61        return decryptedData;
62    }
63
64    public static void main(final String[] args) {
65        final String iv = "0123456789123456"; // This has to be 16 characters
66        final String secretKey = "Replace this by your secret key";
67        final Main crypto = new Main();
68
69        final String encryptedData = crypto.encrypt("This is a test message.", iv, secretKey);
70        System.out.println(encryptedData);
71
72        final String decryptedData = crypto.decrypt(encryptedData, iv, secretKey);
73        System.out.println(decryptedData);
74    }
75}